Immune gene expression and epigenetic potential affects the consumption of risky food by female house sparrows

Cedric Zimmer, Haley E. Hanson, Marisa Garrison, Darrys Reese, Roi Dor, Jørgen S. Søraker, Phuong Ho Thu, Elizabeth L. Sheldon, Lynn B. Martin

Research output: Contribution to journalArticlepeer-review


When organisms move into new areas, they are likely to encounter novel food resources. Even if they are nutritious, these foods can also be risky, as they might be contaminated by parasites. The behavioural immune system of animals could help them avoid the negative effects of contaminated resources, but our understanding of behavioural immunity is limited, particularly whether and how behavioural immunity interacts with physiological immunity. Here, we asked about the potential for interplay between these two traits, specifically how the propensity of an individual house sparrow (Passer domesticus) to take foraging risks was related to its ability to regulate a key facet of its immune response to bacterial pathogens. Previously, we found that sparrows at expanding geographic range edges were more exploratory and less risk-averse to novel foods; in those same populations, birds tended to over-express Toll-like receptor 4 (TLR4), a pattern-recognition receptor that distinguishes cell-wall components of Gram-negative bacteria, making it the major sensor of potentially lethal gut microbial infections including salmonellosis. When we investigated how birds would respond to a typical diet (i.e., mixed seeds) spiked with domesticated chicken faeces, birds that expressed more TLR4 or had higher epigenetic potential for TLR4 (more CpG dinucleotides in the putative gene promoter) ate more food, spiked or not. Females expressing abundant TLR4 were also willing to take more foraging risks and ate more spiked food. In males, TLR4 expression was not associated with risk-taking. Altogether, our results indicate that behaviour and immunity covary among individual house sparrows, particularly in females where those birds that maintain more immune surveillance also are more disposed to take foraging risks.

Original languageEnglish
Pages (from-to)6-13
Number of pages8
JournalBrain, Behavior, and Immunity
Early online date27 Mar 2024
StateE-pub ahead of print - 27 Mar 2024

Bibliographical note

Copyright © 2024 The Author(s). Published by Elsevier Inc. All rights reserved.


  • Foraging risk
  • Infection
  • Invader
  • Neophagia
  • Neophobia


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